dually,,call ted at opel,,he did all the machine work on my x18's engine..i dropped it off on a monday and all the machining was done on friday..and it was all spot on! i assembled the engine 13 yrs ago and it gets abused every weekend and the engine see's 6+ k rpms at any givin moment..

spend the extra money and have bob madera make the cam and have opel do the machining and assembly then dyno the engine..they also hace a cnc which most places dont..

http://www.opelengineering.com/

I can tell you how to spend a ton of money on 420's

I will say I spent the core money on parts that I could use on further builds. Buy it once and buy it right.
I refreshed my 420's with JE/SRP pistons, new ported aluminum Dart heads, best valves and springs. Most of my money is in my heads. But the heads have been on my 454's to blown 572's. After building the 454's to to their max I am now stepping over to the dark side. (positive displacement pumps on top of intake manifolds) Just do a cam swap and bolt on the blowers.

So in short what I am saying is build it with the future in mind. You will get bored with 525 soon.

I agree. I didn't recommend the blower thing as I believe in another thread he didn't have the room for one with his hatch.

But at 500 hours, I'd be getting serious about what you wanna do with that engine.

525 hp at flywheel or prop?

My buddy redid his merc 400 cyclones in his mistress last season, with stock heads, cam was 236/243 duration, around .575 lift, dual plane Edelbrock RPM intake and stainless marine exhaust with 800 holleys, made 521 hp @5300 I forget the torque nbumber but it was pretty good too, I thought it did well for stock head engine at lower RPM's

Jim just did a 502mag M1 Procharged and I was really impressed with the #'s. I think that would fit under the hatch. Shoot have a fresh 700hp 502 in the shop that would also work. cig20 just step over the 525hp mark and go straight to where you want to be

motor comes out this weekend and off to shop

Sounds like a nice 454 build. Roller cam?

Flat tappet Edelbrock RPM cam, I will see if I can find grind number...

We both have Mistress's and mine has stock 420 cams still with Merlin heads and Single plane intakes, we are with 1 mph of each other, I may do more cam this winter thinking there is a decent gain there, mine are also 460CI 8.4:1 so I wanna add a point of compression too...have abest of 65 on gps so farboats heavy as fuk..

You got flat tops in yours? Sound like a candidate for a pair of blowers....

No blowers!! Lol I plan to keep it n/a and simple then I don't blow chit up all the time.... Simple and turn key